Abstract:
An ac–dc single-stage driver for high-brightness light-emitting diodes (HB-LEDs) with galvanic isolation is presented in this paper. The driver is based on a dual inductor current-fed push–pull converter with each inductor operating in boundary conduction mode (BCM). The interleaving between the two inductors enables the converter to reduce the high input current ripple inherent to a BCM. Moreover, it is fully compliant with IEC 1000-3-2 Class C and it is able to achieve a high power factor (PF). Its low component count, simplicity, and overall outstanding characteristics make this current-fed topology suitable for medium power range HB-LED drivers in low-cost applications. The proposed topology has been tested on a 100-W prototype for the full range of the US single-phase line voltage, feeding several HB-LED strings, with an output voltage equivalent to 48 V at full load. The prototype achieves a maximum efficiency of 92% with a 0.99 PF, 8% total harmonic distorsion at full load while guaranteeing a good quality light.